2005IAUC.8555....2R

M. W. Richmond, Rochester Institute of Technology, reports that deep Hubble Space Telescope images of M51 (Hubble Heritage Project) taken in January 2005 show a cluster of young stars near the position of SN 2005cs (cf. IAUC 8553). The object closest to the position of the supernova on Itagaki's image is at R.A. = 13h29m52s.803, Decl. = +47o10'36".52 (equinox 2000.0). This is a blue star; assuming E(B-V) = 0.10 based on the Na I D absorption reported by Modjaz et al. (above), the candidate has intrinsic colors B-V = -0.2 and V-I = -0.4 and, assuming a distance of 8.4 Mpc to M51, an absolute V magnitude of roughly -6. If this blue star was indeed the progenitor, one might expect SN 2005cs to evolve like SN 1987A, another type-II supernova with a blue progenitor.